Poweb-distribtjtiow system



BEST AVAILABLE COP\ Dec. 28,1926. 1,612,063

E. w. SEE GER POWER DISTRIBUTION SYSTEM Filed Sept. 24. 1923 3 Sheets-Sheet l INVENTOR Mmsw ATTORNEY BEST AVAILABLE COPi Dec. 28 1926. 1,612,063

E. w. SEEGER POWER DISTRIBUTION SYSTEM Filed Sept. 24. 1923 s Sheets-Sheet 2 INVENTOR fimhm'm 1113a,

ATTORNEY BEST AVAILABLE COPX Dec. 28 1926. 1,612,063

E. w. SEEGER POWER DISTRIBUTION SYSTEM Filed Sept. 24. 1923 3 Sheets-Sheet 3 ife F INVENTOR ATTORNEY Patented Dec. 28, 1926.

I UNITED STATES BEST AVAILABLE COP.

Persist oFricE.

EDWIN w. SEEGER', or MILWAUKEE; WISCONSIN, Assronon'ro THE CUTLER-HAMMER MFG. 00., or MILWAUKEE, Wisconsin, .9. CORPORATION or WISCONSIN.

POWER DISTRIBUTION SYSTEM.

Application fild September 24;.192 3.- Serial No. 664,468.

This invention relates to power distribution systems.

The invention isparticularly applicable to automatic substations. including two rotary transformer units either: to supply a distribution circuit under light load conditions and theaother to operate .i-n..parallel with the former under heavier-load conditions.

Thelpresent. invention has among its ob.- jects toprovidean improved automatic-controller for. substations of the aforesaid :character:

Another. object is. to, provide. an automatic controller for. substations of. the aforesaid character includingsepa-rate automatic starterszfor each of the units and automatic meansfor starting and stopping either of the uni-ts while the. other is m operationv upon given load conditions in the distribution circuit.

Another objeetis to provide anautomatic controller of. the aforesaid character adapted when either of theunits is in. operation to start the other ofthe units upon a lapse. of time variable inversely to the value. of the load.

Another object is'to provide for equalization of the voltage of the. two units when the same are thrown inparallel across the distribution circuit.

Another object is to provide an automatic controller of the aforesaid character including means whereby either machine when operating alone will be disconnected from the load circuit automatically when its load becomes excessive and whereby the other machine will then be. started and both machines connected to the load circuit.

Another object is to insure against simul taneous starting of the units-after voltage in the supply circuit fails andis restored.

Various other objects and advantages of the inv entionw*lllhereinafter appear.

The accompanying drawings illustrate an embodiment of the-invention which will now be described, it. being understood that certain features of. the invention are not limited to substationsof he character shown and that the controller canbe modified in. certain res ec'ts without departing from the scope of tiie appended claims.

In the drawings:

Figure 1 is a diagrammatic view of a, controller embodying the invention,

Fig, 2 is a diagrammatic view of one or" the automatic starters shown in Fig. 1.

Fig-.- 3 is a so-cal'lcd across-thc-line diagram of the preferred circuit connections, and

Fig. 4c. is a. diagrammatic View of an automatic reclosing circuit breaker which is employed in the distribution circuit Referring to Fig. 1, thesame illustrates an automatic. substation including two motor ge erator sets MG and MG, a three phrase.

flternfating current supply circuit indicated bv'linesL, L L and a dist 'ibution circuit indi cated lines DC. The motor generator: sets each include a motor having an. armature A and afield F and a generator having an armature A, a series field F and a shunt field F The motor generator. sets MG and MG are adapted. to bestarted selectivelf by automatic starters S and. SE, and, as hereinafter set forth autornatic control means is provided between said starters which .is adapted to start either of the motor. generator sets while the otherv operationupon given load conditions in the. distribution circuit.

Also, as. hereinafter set forth, an automatic reclosi'ng. circuit breaker GB is provided for disconnecting both of the motor generator sets from the distribution circuit DC upon no voltage or given overload conditions in. said circuit.

The automatic starters are of like construction and as shown in Fig. 2 each of the same includes a five pole electromagnetic starting switch 1 and a three pole electromagnetic running switch 2 the former switch being adaptedto establish low voltage connections from lines L, L L to armature A through the medium of compensator windings 3 and 4 and the latter being adapted to connect said armature directly to saidlines. The field F of the motor is controlled electromagnetic switches 5 and 6 the former swit h having normally closed contacts 5?- and normally open contacts 5 and the latter having normally open. con.- tacts 6?. comes 5. are adapted to shortcircuit the field F otthe motorthrough adischarge resistance R andthe contacts 5* and 6 are connected in series and are adapted'to connect said field across the terminals of the generator. An automatic reclosing circuit breaker emon will be hereinafter more metallic co fully described, is provided for connectin the generator to the distribution circuit Du and as hereinafter set forth, means 15 provided for connecting the fields F of the motor generator sets in parallel across the terminals of the leading generator. Each of the shunt fields has included in circuit therewith a resistance ll and a regulating rheostat l.

The automatic control means includes a master switch it) which controls the energizing circuit of a double pole electromagnetic switch 11. Starting switch 1 !5 controlled by the left hand pole 11 of switch 11 through the medium of a normally closed electrothcrnially responsive timing switch 12 and a normal closed electromagnetic relay 13, and hereinafter set forth, said starting switch is provided with normally open auxiliary contacts .1 for controlling its energizing circuit and for also controlling the energizing circuit of relay 13. Timing device 12 can be any suitable type and as .iown the same includes a bi- Ll. strip 12 having a heating coil 12 associated therewith. Relay 13 is provided with auxiliary contacts 13 and upon response of said relay said contacts maintain the same in closed position as hereinafter set forth. Field switches 5 and 6 in w are controlled by a normally open voltage relay lconncctcd across the terminals of the generator and thefield switch 6 has associated therewith normally closed auxiliary contacts 6 for controlling the energizing circuit of a relay 1:5, and normally open contacts 6 for establishing an energizing circuit for the running switch through the medium of switch 11 and normally closed contacts 1= associated with starting switch 1. Relay 15 is adapted to shunt the regulating rbcostat 9 in the shunt field circuit 1 and the resistance It in said field circuit is adapted to be shunted by the right hand pole 11 of switch 11.

The auton'aatic reclosing circuit breaker T has a closing Coil T associated therewith the energizing circuit of said coil being controlled by an overload relay i a normally closed auxiliary switch 17 and a normally open auxiliary switch 2* associated with running s itch Switch 17 normally snunts a resistance r in the energizing circuitof coil 7 and upon closure of the circuit breaker the same is moved to open position and adapted to be held therein by an electromagnetic latching device 18. Latching dcricc '18 is releasable by and operatiiur u-in ling 15'. which is controlled by auxiliary switch '2" and a normally closed auxiliary switch 15 associated with circuit breaker T. Switch 19 is adapted to he move-c to open position upon closure of the circuit breaker and upon opening of the circuit breaker the same is adapted to return to closed position against the action of a dash pot 20.

The function and operation of the aforedescribed starter together with the circuit connections therefor will now be more fully set forth in connection with Fig. 3. Assume that the master switch of either of the starters is moved to closed position upon closure of said switch the operating winding of switch 11 is connected across the terminals of a transformer T supplied with current from lines L L of the supply circuit. Switch 11 then closes and it will be observed from Figure 3 that the left hand pole 11- thereof connects the left hand terminal of transformer T to the operating windings of starting and running switches 1 and 2, and also to the operating windings of relays 13 and 15 and heatin coil 12. It will also be observed that te righthand pole 11 of switch 11 short-circuits the resistance R in the shunt field circuit of the generator. Immediately upon closure of switch 11 the operating winding of starting-switch 1 is connecte to'tlie right hand terminal of transformer T through timing switch 12 and relay 13 while the operating winding of relay 15 is connected to the right hand terminal of said transformer through auxiliary contacts 6 associated with field switch 6'.

tar-ting switch 1 and relay 15 thus respond inmiediately upon closure of switch 11 and the former in responding establishes low voltage connections from lines L L L through compensator windings 3 and 4 to armature A, such connections being apparent from the drawing, and the latter in responding shortcircuits the regulating rheostat 9 in the shuntfield circuit of the enerator. Also it will be observed from 15g. 3 that upon response of starting'switch 1 the auxiliary contacts 1" thereof establish a circuit from the right hand terminal of transformer T through timing switch to the operating winding of 'starting switch 1 and also from the right hand terminal of said transformer to the operating winding of relay 13. Relay 13 thus responds and the auxiliary contacts 13" thereof establish a maintaining circuit therefor from the right hand terminal of transformer T.

Upon establishment of the aforementioned starting connections the motor will be brought up to speed the field thereof being short-circuited through resistance}! by contacts 5", of field switch 5. Assuming that the shunt field F of the generator is connected across the generator terminals and it will be observed that due to exclusion of the resistance R and rheostat 9, as above set forth, the voltage of the generator will build up quickly. The operating winding of voltage relay 14 is connected across the terminals of the generator and when the generator voltage reaches a. predetermined Jim smccii 2- then responds Izilde said relay responds and it is app virent from Fig. 3 that upon response operating windings are connected in' parallel across the generator terminais. Field switches} 5 snd'G then respond and it will be observed from that the some connectthe field F of the motor across he terminals oi the generator throngh regmnting rheostnt R Also, upon response of field switch 6' the auxiliary confzicts 5* they i interrupt the Jllll'gllfig circuit of relay and said relay in opening inserts the regulatio l'iiJGStElT. 9 in the sl'r'nnt field C5; enerzztor. Following z-esponse of l relay 3'2 res ope-r and upon openin'g'of said start- "ie operating windizim of runconnected to the r ght handfoi'nie r T tlirob gli i? =rtiizg switch 1- 3nd switch 6. Running to connect" the' motor ermatiirc A. directly: {o lines L, if :nid L and upon closure of saidirnnning. switch it is spoon-ant from 3 that the closing coil 7 0-. circuit breaker 7 is connected ocross the generator terminals throng]: overload re lay 16, tlllZ-lilifil') switch 17 and auxiliary contacts 2* of sai running: swi'tcl'i. Circuit breaker Tin c.0sm 51 connects the gen'ei zitoi" to thedistribution circuit DC and upon closm'e of said circuitbreaker a'uxili aiv swlch i? inserts the 'ssistnnce win the circuit oi windingff A'lsonpon' closin'e of circuit breaker 'i' auxiliary switch. 19 is moved to open position the latching device 18 then serves to lock switch 11' in open posit-ion. \Vhe'n the load on the. 'eii-w orator is of a predetermined value relay" 16 responds to intcrruptthe energizing circuit of closing coil and upon opening of the circuit breaker, switch 17 is held in open position by latching device 18. However. after a given period switch 19 L etnrns to. closed position against the act-ion. of dosh pot 20 and upon closure of said switch winding-1 8 is connected across the terminals of the gen} era-tor through contacts 2 zissocisiied want running switch The latching device. 18 then rcsponos and switch 17 returns to. closed position to short-circuit the resistance r and if-th overload relay 16 hasrotu'rned to closed gzosition winding 7- is energized toeffeet reclosure of the circuit breaker As before stated, means is. provided for connecting the shunt fields 1 of the gen rs in pznmilcl across the terminalsoi h: ding generator. and, as shown-imFi g. 1 means con es :1 two pole double knife sw tch It isoppnrent that ith the circuit connections shown in. Fig.1

'e= oft-he. linifelswitch into engageits left hand stati o nziry \"m'xincls thereof the of field switches 5'and 6 ies and 6 the timing" BEST AVAILABLE cop connects the'filds F" in parallel across the terminals of tli left hiih'd generator, while' mo enientof the knife switch into engage- In'nt with its right h'and stationary contzi'cts connects said i the terminals of the'ri'ght blind generator. Also, as shown in Fig: I, a'swi'tch 26 is prw filed for establishing an eqna'li'zing' cenfieldsvin parallel across neci'ion' between the generators of the two cont'alcts 3'2 to inclusive and said drum is mowziblein opposite'dii'ctions ironi an intermediate oil? position into ext c on position Contacts 28 to 3'1 int-his e co-operatewith sfigi'tiona'ry contacts 28" to 31. 28* to 33) and '28-t o 31 while contacts to35 inclusive comptz'rhtelwith stationary contacts 32 to 35", 32 to 35 and 32 to 35. 'I'hcpilot switch PS comprises a movable dr in'i hzivinglelectficzilly connected contacts 36' to 40 which co-o'pemte with stz'i'ti'onzn contacts 36ft'o40ies'pedifily. Pilot switc 1 PS'is adapted to'be di iven' in opposite directions by aniotorl, said motor having an nrmz tnre 41 is'conti olled by '3 hil: of double pole electromagnotio switches 42, and 43, the former swit i, heving a' field COiltIOl contiiet 42 associated thenewith and being adapted to s b sh n' i e n ctio s f nw o rationoi th'motofandthela tteg hzivi ng 2i. ontwli 43; aissbeiaftd therewith and being adapted toe'stablisliroveifse' pews; connections for the motorl hereinafter setfoflh, the power connections established by switch, 42', 1nolnd'e resistances 17 and r while',th power; connections established by switch 543 inclufd, additionto the afore said re'si'stan'es, resistances?! end-r. Also, asherina'ftef s'et'gforth, the resistance a" is dap e fi fs ude oh he'p er i cuii't of the moto'r' by: a norrnollyclosed relay 4% 2mm to'giyiiloild conditionsthe cli'stnibution circilit, Switches 42 and 43 zi1' e controlled. :ela'ys 45" :ind' fi. Relay 45 is controlled by norrng lly open auxiliary contacts 7; associeted with eaoh oi: the eirciiit brcakei' s.'7 end. sziid' relay is iisp fsivfe to iioltzig'e in' th e' distribiltion' cil nitand includesa.- contzict Inenibernori'iiiil'ly in. ehgoigement witl1 a stat'ionnr' cantor); 45 Inovable i to ng-a gein'ent with a stntiQnary contact membe'r45i. Relay 46 responsive to. given load conditions in the distribution cinciiit andth sarne inclnde'sja' contoctmeniher normsll 1n en a ement with :1 stationof" a transfer ary contact 46 and movable into engagement with a stationary contact 46.

The function and operation of aforedescribed automatic control means will now be more fully set forth in connection with Fig. 3. Assume that the motor generator set MG is in operation and that the transfer switch TS is in its upper position. .lf the load on the distribution circuit is normal circuit breaker 7 of starter i. 1 is in closed positionand it is apparent from Fig. that the contacts 7" thereof connect the winding of relay 45 across the distribution circuit whereby the movable contact'of said relay is held in engagement with its co-operating stationary contacts 45. Relay 46 responds upon given load conditions in the distribution circuit- DC while relay 44 responds upon heavier load conditions. Relay 46 in responding establishes an energizing circuit. for switch 42 extending from the left hand terminal of transformer T associated with starter S through contacts 29", 29 and 29 of the transfer switch through the movable contact and stationary contact 46 of relay 46 through the operating winding of switch 42 through contacts 37, 37, 36 and 36 of the pilot switch through contacts 35, 35 and 35 of the transfer switch through auxiliary switch 6 associated with field switch 6 of starter S to the right hand terminal of said transformer. Switch 42 then responds and in responding the same establishes power connections for motor 41 extending from the left hand terminal of the generator of set MG through contacts 28128 and 28'" of the transfer switch through resistance r and the right hand pole 42 of switch 42 through armature a through the left hand pole 42 of the switch 42 through contacts 34. 34 and 34 and 33 of the transfer switch to the right hand terminal of said generator.

It should be observed upon establishment of the aforedescribed power connections, resistances r and r are connected in parallel across the terminals of the armature a of motor 41. while the auxiliary contacts 42 associated with switch 42 connect the field 7 of said motor across the terminals of the generator of set- MG. Motor 41 then operates to move the pilot switch in the forward direction indicated in the drawings and after a given period of time contact 39 is brought into engagement with contact 39 to encrgize switch 27 by a circuit extending from the left hand terminal of the transformer T associated with starter S through cont-acts 29 29 and 29 of the transfer switch through the operating winding of switch 27 through contacts 39 and 39 to contact 36 of the pilot switch through cont-acts 35, 35 and 35 of the transfer switch through auxiliary contacts 6 of the field switch 6 associated with starter S to the right hand arminal of transformer T. In responding switch 27 shunts master switch of starter S by a circuit extending from the left hand terminal of said master switch through contacts 31, 31 and 31 of the transfer switch through the right hand pole 27 of switch 27 through contacts 30 and 30 of the transfer switch to the right hand terminal of said master switch. Upon shunting of master switch 10 of starter S said starter functions in the manner above described to start the motor generator set MG? Switch 27 in responding is maintained in closed posit-ion pending return of the pilot switch to normal position by a circuitextending from the left hand terminal of transformer T associated with starter S to and through the winding of switch 27 as already traced through the left hand pole 27 of switch 27 through contacts and 40 to contact 36 and thence to the right hand terminal of said transformer as already traced. As soon as the voltage relay 14 associated with starter S responds, switc 26 is energized by a circuit extending from the left hand terminal of the generator associated with set MG through said relay through contacts 32 32 and 32 of the transfer switch through the operating winding of said relay and through contacts 33, 33, 33 and 34 of the transfer switch to the right hand terminal of said generator. In responding switch 26 establishes an equalizing connection between the generators which is apparent from the drawings. Immediately upon closure of relay 27 to effect automatic starting of the generator set MG contact 37 of the pilot switch moves out of engagement with contact 37 and the switch 42 is then deenergized to interrupt the power connections of motor 41 for stopping the latter.

As before stated, relay 44 responds at a higher load value than that at which relay 46 responds. Relay 44 in responding excludes the resistance a in the energizing circuit of motor 41. and said motor thus operates at a given speed in a forward direction upon given load conditions in the distribution circuit and at a higher speed upon increased load conditions in said circuit whereby the pilot switch PS functions to start the second motor generator set upon a lapse of time variable inversely to the value of the load.

Assume now that the pilot switch PS is in its full forward position or in any intermediate position and that the load on the distribution circuit drops so that relay 46 returns to normal position. Switch 43 will then be energized by a circuit extending from the left hand terminal of the transformer T associated with starter S through contacts 29 29 and 29 of the transfer switch through the contact arm and stationary contact 46 of relay 46 through the contact arm BEST Ai/AILABLE COP\ connections for motor 41 extending from the left hand terminal or the gen ator associated with set MG through con acts 28, 28 and 28 of the transfer switch through resistance r and the right hand pole of switch d3 through armature a through resistance 1- and the is it hand pole -13" oi switch 43 through con tarts 3 c-;:, 33-2 and 33 of the transfer switch to the right hand terminal of said generator. It should be noted that upon estabhshi. out of. the aforedesa'ribed connections for motor 11, contact 43 associated with switch connects the field f across the terminal of the generator or" setMG. Thus, the motor f l will operate in a reverse direction at a speed which is less than its speed in a forward 'directioirand assuming that the load on the distribution tirt-uit remains below the value at which reia 4-6 responds the pilot switch PS will return to its normal position. Upon return of the pilot switch PS to normal position Contact 88 disengagcs contact 38 to open switch 43 for stoppingofmotor 41 and if the motor generator set- MG is in operation the same is stopped by opening of switch 27 through disengagement of contact 40 from contact 40.

Assume now that the motor generator set MG" is in-oper'ation and that the transfer switch TS is moved into its lower position, relay 45 will then becontrolled by contacts 7 of the circuit breaker 7 associated with starter S and said relay and relaj &5 will function to control the energizing circuit of switches 42 and 43 in the manner above-described t'o efiect forward and reverse operations of the pilot motor 41. However, switches 42 and 43 will then be energized from the transformer T associated with starter S and the pilot motor 41 will then be energized by current from the generator of the set MG". Circuit from transformer 'l of starter S to the witches 42 and 43 is then established through contact 29 and 35 of the transfer switch and contacts 6 associated with the field switch of starter S while the circuit from the terminals of the generator set MG to Jilot motor 41 is established through contacts 28 and 34. of said transfer switch. Also with the transfer switch in its lower position switch 27 serves to short-circuit the. master switch 10 of starter 1 by a. circuit extending through contacts and 31 of said transfer switch and switch 26 issupplied with current from the generator of tes 3. an

close for automatic set MG by a circuit extending through contacts 32 and 33 ofs id transfer switch.

l-Vhen either of the motor generator sets is in operation and the load thereon exc'eeds a predetermined value, the circuit breaker 7 associated therewith opens, and the contacts 7 thereof open th energizing circuit of relay -t5 If the motor generator set MG is in operat-ion and the circuit breaker '7 associated therewith opens, relay 45 estabiishes an energizing circuit for switch l2 extending from the left hand terminal of the transformer/l associated with the starter S through contacts "2-9 29 and 29 of the transferswitch through the contact rm and stationary c'ontact''o of relay 46 throu h the contact arm and stationary contact'fio of relay -15 through the (n ieratingwinding of switch 42 through contacts'i-ZTF. 37 to '36 of the pilot switch through con- .ss 'of the Itransii' switch anjdthrough contact (3 of 'theffield swit'cli of startejr s to the 'righthand terminal of th= transformer. llowevenif ,themotjor generator set' dc isiii operation and the circuit breallzer 7 associated therewith opens, relay 1-15 establ shesa'n energizing circuittor switch l-2 entending from the left liarid'lterininal of the transformer T associated with starter 15'' through contacts 2932 9 and 2930f the transfer switch through the contact arm and stationary contact 4.6 of rl ay* l6 through the contact arm and stationary Cbl'lt'zicfiflS of rela -a5. through the "operating winding of 'switchjl through contacts 321-37 to contact 36" of the pilot switch through contacts 35 and a5? or Saga transfer swash ma thencethrough the auxiliary contact 6 of field switch 6. to the right? hand'tei'min al o'l transforinrT; 4

Asahoi'eset'fortli, closure ofswitch 42 effects forward 9 era-tioii offthe pilot niotor 41 which operation'cai ses the switch 27 to startingof the idle motor generator set." it is apparent that when ither'blttlieni'ot {generator sets is in-operation and'the' circuit breaker? associated therewith opens the ib therniotor' geiieriitor sct. will'be autoinatically' started.

A's 'ab'or'e stated, air automatic reclosing circuit brealter'ClB proi ided'inthe distribiition circuit." As shown-iii Fig. l 'circuit 'b1'eaker "(3B is pror'dd with a closing: coilfS the erier izing circuit of said 'coil'hein controlled y an overload relay 49 and an aaixiliary switch 50. Ore'rload relay s t) is responsiveto load conditions inthe disvtribiition circuit whilethe switch 50 is biased to closed position-and upon closure of the circuit breaker tbe'satne is moved to IOU rent to the operating coil to an amount just sufficient to hold the circuit breaker in closed position but insuflicient to move the same from open position. Latch 51 is provided with a tripping coil 52, the energizing circuit of said coil being controlled by normally closed auxiliary switch 53. Switch 53 is adapted to open upon closure of the circuit breaker and upon open'ng of said circuit breaker the same moves to open position against the action of dash 0t 54. The control means further includbs resistances r, and r, said resistances being connected as shown in the drawing.

With the parts of the circuit breaker in the position shown in Fig. 1 it will be observed that if the current conditions in the distribution circuit are normal, tripping coil 52 will be energized by a circuit extending from point 55 in one of the lines through resistance 1* through said tripping coil and through the auxiliary switch 53 to point 56 in the other line. Tripping coil 52 will thus release latch 51 for closure of switch and said switch in closing excludes the resistance r", The operating coil 48 is then connected between points 55 and 56 and the circuit breaker will then close and will remain in closed position as long as the current conditions in the distribution circuit are normal. Upon voltage failure the winding 48 will be deenergized and the circuit breaker will reclose only after the dash pot retarded switch 53 returns to closed position. Upon overload conditions in the distribution circuit relay 49 opens to interrupt the energizing circuit of switch 48 and the tripping coil 52 will remain unresponsive until the current conditions in the distribution circuit return to normal. Assumin that the circuit breaker has been trippe and the parts are in the position shown in Fig. 4 it will be observed that when overload or short circuit exists in the distribution circuit DC, there are two paths whereby current may flow from the point 55 to the point 56 one of said paths being through the resistance a, coil 52 and switch 53 and the other being through the resistance 1' and the load or short circuit on the distribution circuit. Coil 52 is wound with a low resistance so that a slight variation in the resistance of the load or short circuit on the distribution circuit will cause a corresponding change of current through said coil. Thus if the load or shortcircuit on the distribution circuit is of low resistance, a large part of the current will be shunted around the coil 52 but as soon as the short circuit is removed or the resistance of the circuit increased to a value which would not permit excessive current to flow were the breaker to reclose enough current will pass through the coil 52 to effect tripping of latch 51 for reclosure of the circuit breaker.

BEST AVAILABLE COP\ It will now be observed that upon tripping of either of the circuit breakers 7, the circuit breaker CB will open. As before stated, when either of the motor generator sets is in operation and its associated circuit breaker is tripped the other motor generator set will automatically start. The dash pot 5% of the circuit breaker GB is designed so as to prevent reclosure thereof for a time interval which is sufficient to bring the second motor generator set up to speed and to also permit the circuit breaker of the leading enerator to reclose. Thus upon reelosure c l o of circuit breaker CB the motor generator sets will be thrown in parallel across the distribution circuit. As long as the load in the distribution circuit is below a given value circuit breaker CB will remain in closed position but under abnormal load conditions the relay 49 will respond to effect opening thereof. However, the two motor generator sets will remain in operation and as 'soon as the load conditions in the distribu tion circuit return to normal the circuit breaker CB will reclose to reconnect the ii motor generator sets to the load.

As before stated, means is provided for connecting the fields of the two generators in parallel across the terminals of the leading generator. The fields are connected in 1 this manner to maintain the fields of the leading generator and the idle generator at substantially the same heat to provide for equalization of the terminal voltage of the generators when the same are thrown in parallel across the distribution circuit. Further, it should be noted that upon failure of voltage in the supply circuit both of the automatic starters S and S will return to normal position and upon restoration of the "oltage in said circuit the leading motor generator set will be brought up to speed prior to starting of the other motor generator set.

"What I claim as new and desire lo z-tc'cm'r by Letters Patent is:

l. The combination with an alternating current supply circuit and a direct curl-a .:3 distribution circuit, of a plurality of reuntransformer units to he roiuu-clwl in pa cl between said cirruits. automatic means for starting said units from said supply circuii subject to manual selection and for connecting the same upon starting thereof to 5 distribution circuit, and means for automatically startingand stopping either of said units while the other is in operation upon given load conditions in said distri bution circuit, said latter means comprising? means for varying the starting period oi said former unit.

2. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality of rotaq transformer units to be connected in parallel between said circuits, means for selectively starting saidunits from the former circuit and for connecting the same to said latter circuit u on starting thereof and automatic means acapted when either of said units 15 in operation to start the other of said units after a given period of time upon given load conditions in said distribution circuit and in a shorter period of time upon increased load conditions in said distribution circuit.

3. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality of rotary transformer units to be connected in parallel between said circuits, means for selectively starting said units from the former circuit and 101' conne-ctiug the same to said latter circuit upon starting thereof and automatic means adapted when either of said units is in operativeto startthe other of said units when the load on said former unit exceeds a given \"a-lve, said means bei adapted to start. said latter unit after a period of time. raryinginvcrsely to the value otthe load on said former unit.

-:l. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality. of rotary transformer units to be connected in parallel between said circuits, separate automatic starters for said units, eaclradapted to startits respective :unit from said supply circuit and each including an automatic reclosing overload circuit breaker for connecting its respective unit to said distribution circuitupon starting thereof and automatic means between said starters for automatically starting either of said units while the other is in operation, said means being adapted upon opening of the circuit breaker associated with either of said units to start the other of said units.

5. The combination with an alternating current supply circuit and direct current distribution circuit of a plurality of rotary transformer units to be connected in parallel between said circuits, an automatic starter for each of said units adapted to start the same from said former circuit and to connect the sameto said latter circuit upon starting thereof, each of said starters being pr videdu'ith a master switch for controlling the same and control means between said starters adapted when either of said units is in operation to shunt the master switch associated with the starter oi the other of said units for starting of the latter upon given current conditions in said distribution circuit.

6. The combination with an alternating! currentsupply circuit and a direct current distribution circuit of a plurality oi rotary transfor ier units to be connected in parallel between said circuits, an automatic starter for each of said units for starting the same BEST AVAILABLE COP\ from said former circuit and for connecting the same to the latter upon starting thereof, each of 'said starters including a master switch forcontrolling the same,= and means adapted when operation to start the other of the said units by shunting the master switch associated with the starter of the latter, said means being adapted to act-after a. given period of time upon given load conditions in said distribution circuit 'and in a shorter period of time upon predetermined increased load conditions in said circuit.

7 The combination with an alternating current supply circuit and a: direct currentdistrihuticn circuit of a pluralitv of rotary transformer units to be connected in parallel between said circuits, -means for starting said units selectively from-said former'circuit and means adapted when either of=said units is in operation to start theo'ther of said units upon given load conditions in'said distribution 'circiiit,= said mea'ns including :a timing device adapted to act after a. given interval upon'predetermined load conditions in said distribution circuit a d in a-shorter interval upon predetermined increased load conditions in said circuit.

8. The combination with ail-alternating current supply circuit and .a. direct currentdistributioncircuit of a: plurality of motor generator sets to be connected parallel between said circuits, the generator of each of said sets having a shunt field winding, automatic means for starting said sets from said supply circuit subject to manual selection and for connecting the same upon starting thereof to said distribution circuit, means associated with said former means for automatically starting and stopping either of said sets, While .the other is in operation, upon given load conditions in said distribution circuit and means for connecting the shunt field of the generator of either of said sets in parallel. with the shunt field of the generator of the other of said sets while the latter set is in operation to render the voltage of the former set upon start-in thereof substantially the same as the v0 tage of the latter set.

9. The combination 'ith an alternating current supply circuit and a direct current distribution circuit of a. plurality of motor generator sets to be connected in parallel between said circuits, the generator of each of said sets being provided with a shunt field winding, a regulating rheostat in the shunt field circuit of the generator of each of said sets, means for starting said sets from said supply circuit subject to manual selection and for connecting the same upon starting thereof to said distribution circuit, switches associated with said former means for excluding said rheostats from the shunt field circuits of the generators during starting of either of said units is in said sets, and means associated with said former means for automatically starting and stopping either of said sets while the other is in operation, upon given load conditions in said distribution circuit.

10. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality of rotary transformer units to be connected in parallel between said circuits, separate automatic starters for said units, means associated with said starters for automatically starting and stopping either of said units While the other is in operation upon given load conditions in said distribution circuit, said latter means being adapted upon failure of voltage in said supply circuit to insure againststarting of both of said motor generator sets upon restoration of voltage in said circuit.

11. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality of rotary transformer units to be connected in parallel between said circuits, separate automatic starters for said units adapted to start the same from said former circuit and to connect the same to said latter circuit upon starting thereof and means associated with said starters for automatically starting and stopping either of said units while the other is in operation upon given load conditions in said distribution circuit, said latter means including a motor operated timing device adapted to start the former unit in a given period upon given load conoitions in said distribution circuit and in a shorter period upon increased load conditions in said distribution circuit.

12. The combination with an alternating current supply circuit and a direct current distribution circuit of a plurality of rotary transformer units to be connected in parallel between said circuits, separate automatic starters for said units each including a circuit breaker for connecting its respective unit to the distribution circuit upon starting thereof, said circuit breakers being adapted to open upon given load conditions on their respective units and being adapted to reclose automatically after a given period of time, means associated with said starters r'or automatically starting either of said units while the other is in operation upon opening of the circuit breaker associated with the latter unit, and a circuit breaker in said distribution circuit adapted to open upon opening of the circuit breaker associated with said latter unit and to reclose automatically after starting of said former unit.

In Witness whereof, I have hereunto subscribed iny name.

EDVVIN W. SEEGER. 

